Barcode systems have been widely used in various aspects, such as automated logistic management, anti-counterfeit, labels, etc. In one application, a two-dimensional barcode or a QR code may be printed on a poster or digital contents for protecting copyrighted content from illicit and unauthorized use. However, the additional printed barcode or QR code may adversely affect the overall esthetics of the poster or digital contents.
Another anti-counterfeiting manner involves using steganography to conceal message (regarding the copyright) in the documents and images. For example, U.S. Pat. No. 8,594,453 discloses a conventional method for creating a data-bearing halftone image in the form of a stegatone (steganographic halftone).
As shown in FIG. 1, a cell of a grayscale image may be converted into a stegatone using one of the four stegatone cells 502, 504, 506 and 508. Each of the stegatone cells is associated with a binary code having two bits (e.g., ‘00’, ‘01’, ‘10’ and ‘11’). As such, a message (e.g., a copyright claimer) in the form of a stream of binary codes may be represented by a series of stegatone cells which composes the data-bearing portion of the data-bearing halftone image, eliminating the need for a barcode.
However, an amount of data that is able to be contained in each of the stegatone cells 502, 504, 506 and 508 is limited to two bits. Specifically, in each of the stegatone cells, only four possible combinations of arrangements exist. Moreover, the arrangements of the grayscale image using the stegatone cells are deliberately made. As a result, the quality of the generated data-bearing halftone image may be compromised as well.
Other related documents regarding generation of a data-embedded halftone image includes:
Xu, Jianyun, et al., “JPEG Compression Immune Steganography Using Wavelet Transform,” Proceedings of the International Conference on Information Technology: Coding and Computing, Las Vegas, Nev., Apl. 5-7, 2004, vol. 2, pp. 704-708;
Solanki, Kaushal, et al., “‘Print and Scan’ Resilient Data Hiding in Images,” IEEE Transactions on Information Forensics and Security, vol. 1, No. 4, pp. 464-478, December 2006;
Ulichney, Robert, et al., “Encoding Information in Clustered-Dot Halftones,” Presented at the 26th International Conference on Digital Printing Technologies, Sep. 19-23, 2010; and
Chiew, Kang Leng, et al., “Identifying Steganographic Payload Location in Binary Image,” PCM′10 Proceedings of the 11th Pacific Rim Conference on Advances in Multimedia Information Processing: Part I, Shanghai, China, Sep. 21-24, 2010, pp. 590-600, Published by Springer-Verlag, Berline, Heidelberg, 2010.